Abstract: In order to achieve real-time visualization detection of the grouting process of the dam, a dual channel cross hole radar and automatic positioning control system were applied, combined with real-time imaging algorithms, to conduct CT detection of the layered grouting process of the Shiziping Dam. The electromagnetic wave velocity and attenuation anomalies presented by the slurry diffusion were tracked, and the range of slurry diffusion and the time required for stability were analyzed. By comparing the electromagnetic wave velocity images and attenuation images before and after grouting, it was found that there was a significant improvement in the compactness and impermeability of the medium after grouting. The experimental results showed that the dual channel cross hole radar can achieve visual detection during the dam grouting repair process, providing assurance for the engineering quality of dam grouting process.